a-, without; 0,un, leaven), a name given by the Orthodox Eastern to the Western or Latin Church, because of the latter's use of unleavened bread in the Eucharist, a practice which arose in the 9th century and is also observed by Armenians and Maronites following the Jewish passover custom.
The Orthodox Church strenuously maintains its point, arguing that the very name bread, the holiness of the mystery, and the example of Jesus and the early church alike, testify against the use of unleavened bread in this connexion.
In memory of this the Israelites were for all time to eat unleavened bread (matzoth) for seven days, as well as keep the sacrifice of the Passover on the eve between the fourteenth and the fifteenth of Nisan.
Lengerke recognized a double motive: the lamb for atonement, the unleavened bread as a trace of the haste of the early harvest.
The feast of unleavened bread to be kept seven days at the time appointed in the month Abib.